The present invention relates to electric plugs, and relates more particularly to a dual-use electric plug which has a movable grounding prong can be alternatively set between the working position and the non-working position.
Regular electric sockets can be commonly divided into two groups, namely, the two-pole electric sockets, and the three-pole electric sockets. An electric plug for two-pole electric socket has two blades for connection to the black wire and the white wire respectively. An electric plug for three-pole electric socket has two blades for connection to the black wire and the white wire, and a grounding prong for connection to the grounding wire. Because an electric plug for three-pole electric socket has a grounding prong, it cannot be coupled to a two-pole electric socket. If to connect an electric plug for three-pole electric socket to a two-pole electric socket, an adapter shall be used. As illustrated in FIG. 1, the electric plug, referenced by 10, has two blades 11 and 12, and a grounding prong 13. The adapter 14 has two blades 15 and 16 at the front side for connection to the black wire and the white wire, and three plug holes (not shown) at the back side for receiving the blades 11 and 12 and grounding prong 13 of the electric plug 10. When the adapter 14 is attached to the electric plug 10, the electric plug 10 can then be connected to a two-pole electric socket. However, if the adapter 14 is not available, the electric plug 10 cannot be used for connection to a two-pole electric socket.